Class III

Question 1

Which is better. matrix + wedge before bond or after?

Answer 1

before. better bc bond doesn’t go to other tooth.

Question 2

How is wedge/clear strip placed?

Answer 2

Question 3

In SIM where do you ACCESS class III prep?

Answer 3

abt 0.5-1mm GIGIVAL (towards gum) to the contact point
- basically = closest bit touching next tooth, w/o damaging it
- bur is at AN ANGLE 90 degrees (straight on) to surface of the tooth

Question 4

Where does caries normally occur in class III preps?

Answer 4

gingival to contact point

Question 5

Explain how bur should be positioned when accessing and drilling?

Answer 5

don’t go straight on a sloped surface. 90 degrees. follow the flow of sf 90 DEGREES

Question 6

SIM outline protocol is most demanding practice of Class III. Ideally you will just go where caries is. But for SIM what are outline ft to follow?

Answer 6

• 3mm height from proximal contact down to gum
• 0.5mm min of contact area
• depth: half of labial margin
• labial wall parallel to itself, dont drill based on palatal

Question 7

IN SIM for Class III what proximal shape are you aiming to create? why?

Answer 7

Clinically, after removing caries, the labial margin is frequently still in contact with the adjacent tooth. In preclinical work, however, the labial margin of the cavity is usually free of contact. On the palatal surface, the optimal extension should be no further than half-way across the
palatal marginal ridge.
In order to protect the incisal corner of the tooth, ideally, the incisal part of the cavity will often tend to have a teardrop shape (proximal view)

narrow to the tip

Question 8

Key steps for Class III outline in SIM

Answer 8

1. access at angle
2. water
3. extend towards labial, past 1/2 width of tooth, parallel to labial.
4. prox: tear tip to the tooth tip
5. palatal= half circle

Question 9

Explain Class 3
a) retention
b) convenience
c) finishing

Answer 9

Question 10

Class 3 step

Answer 10

• access, mid contact point (at least 0.5-1mm) - - 3mm total towards gingival, but at angle to tip
• depth= half way prox
• parallel/straight to labial

Question 11

Prep criteria

Answer 11

Question 12

dam criteria

Answer 12

Question 13

What are some pulpal irritation causes that could occur during/ post tx?

Answer 13

Question 14

What is used to seal and protect the exposed dentinal tubules close to the
pulp

Answer 14

A thin application of RMGI (e.g. Vitrebond) is used to
seal and protect the exposed dentinal tubules close to the
pulp.

Question 15

The principal
goal of the GI in the Class IV situation is to

Answer 15

From the perspective of potential polymerization
shrinkage of the CR, the C-factor is LOW. The principal goal of the GI in the Class IV situation is to seal the tubules, protecting pulp chamber, especially after trauma

Question 16

Although some clinicians choose to use a “non-matrix” technique with a Class IV situation, in order to optimize the contact with the adjacent tooth, that technique is more clinically demanding for the inexperienced clinician.
Therefore, for preclinical work, it is usual to place:

Answer 16

a clear
matrix strip, which is supported by a wedge (to hold the
matrix still, to minimize excess at the gingival margin, and
to slightly separate the teeth in order to compensate for
the thickness of the matrix strip)

Question 17

a “non-matrix” technique is usually essential when?

Answer 17

In clinical situations where a diastema (gap in front tooth) is being closed, using CR, it is rarely possible to use a matrix/wedge and a “non-matrix” technique is usually essential.

Question 18

Placement of the Composite Resin

Answer 18

Composite resin is placed in several increments. The number of increments will be determined, to some extent by the size of the restoration

Question 19

Size of decay + what other factor would determine the number of palatal composite increments?

Answer 19

firmness of the CR and its resistance to “slumping”

Question 20

How can we further enhance the blending/harmonizing of the CR with
the remaining tooth structure?

Answer 20

Clinically, with the development of different
opacities of quality composite resins over recent years, it has become common practice for a number of different opacities of composite to be used in building up a large
Class IV clinical restoration. In addition, clinicians at times make use of low viscosity resin “tints” and “opaquers” to further enhance the blending/harmonizing of the CR with the remaining tooth structure.

Question 21

What must be achieved on the palatal side of the restoration IV?

Answer 21

dentine colour to avoid darkness

Question 22

or Preclinical work
In early preclinical work, it is common to use just one CR material, with the aim to learn the technical steps in building up this restoration in increments.
At a later stage, students can experience some of the “refinements” in technique during which different shades/ translucencies are used in building up the Class IV
restoration).
In preclinical work, therefore, the following 2 increments are commonly placed, and in what sequence?

Answer 22

Palatal increment: one increment with a body
shade to provide opacity.
- Leave a “labial window” approximately
1mm wide (labio-palatally). This labial window provides space for placement of the labial increment CR.
- Each palatal increment is cured for a total
of 40 sec: 20 sec from the palatal and 20 sec from the labial.

Labial increment: (optimally) ONLY ONE
increment is used for the labial. This is done to
minimise the likelihood of placing voids/ porosities
on the aesthetic labial surface – at the junction of
increments.

• Provides ALL the labial contour for the
  restoration.
• Completes the build-up of the incisal edge.

Question 23

To apply the palatal increment effectively and with
precision requires CAREFUL application of

Answer 23

the matrix.

Placement of a clear matrix on the back side of the tooth held in place with a wedge and finger pressure ensures a surface to build material up against. After curing, the matrix is carefully folded across the labial to:
* Provide adaptation of the labial increment onto
the previous increments
* Provide slightly excessive labial contour
* Provide correct restoration of the proximal-labial
curvature of the restoration, which is critical in
ensuring that the restoration will have adequate
M-D width.

Question 24

Failure to adequately control this “folding” of the matrix will usually result in

Answer 24

a labial contour that lacks adequate
M-D width and for which the proximal-labial corner is excessively rounded.
It is therefore STRONGLY RECOMMENDED that the
clinician uses two hands to control the folding of the matrix. An assistant is required to hold the curing light. This will enable the clinician to vary the tension in the matrix in such a way as to optimize the initial contour of the labial CR.

Question 25

The labial increment is cured for

Answer 25

40 sec

Question 26

Common Alternative Preparation Technique for class IV

Answer 26

Preparation of the margins (“finishing lines”):
- Gingival Margin – ensure the gingival
margin is free of unsupported enamel. Use
of an interproximal strip works well in this
case.
- Palatal Margin – a “butt” margin is
prepared (90 degrees).
- Labial Margin – a bevel is placed with a
long tapering or flame-shaped diamond.

Question 27

Placement of the Class IV Restoration

Answer 27

Question 28

What to consider for restoring Class III:
- placement
- matrix/wedge

Answer 28

Question 29

What to consider for restoring Class III
- bonding
- placement of CR

Answer 29

Question 30

What to consider for restoring Class III
- finishing
-contour
-smoothing

Answer 30